RESUMEN
Headspace solid phase microextraction (HS-SPME) has advantages of high purity of the extract, avoidance of organic solvents and simple technical manipulation and can be used in combination with gas chromatography-mass spectrometry (GC-MS) in the hair analysis of a number of drugs. HS-SPME coupled with the hydrolysis of the hair matrix by 4% sodium hydroxide in the presence of excess sodium sulphate and of a suitable internal standard proved to be a convenient one-step method for the measurement of many lipophilic basic drugs such as nicotine, amphetamine derivatives, local anaesthetics, phencyclidine, ketamine, methadone, diphenhydramine, tramadol, tricyclic antidepressants and phenothiazines. Detection limits were between 0.05 and 1.0 ng/mg. From spiked 10-mg hair samples absolute recoveries between 0.04 and 5.7% were found. These recoveries decreased considerably if larger sample amounts were used, perhaps due to increased drug solubility in the aqueous phase or to elevated viscosity in the presence of dissolved hair proteins. Because of the phenolic hydroxyl group a change of pH after alkaline hair digestion (by adding excess orthophosphoric acid) was necessary for the detection of delta 9-tetrahydrocannabinol (delta 9-THC), cannabinol (CBN) and cannabidiol (CBD) by HS-SPME. Nevertheless, the detection limits were such that only CBN could be detected in hair of a consumer. Clomethiazole, a compound hydrolysed in alkali, was measured by HS-SPME after extraction with aqueous buffer. The detection limit was 0.5 ng/mg. Cocaine could not be detected by HS-SPME. The application of HS-SPME to hair samples from several forensic and clinical cases is described.
Asunto(s)
Cabello/química , Intoxicación/diagnóstico , Detección de Abuso de Sustancias/métodos , Antidepresivos Tricíclicos/análisis , Cannabinoides/análisis , Clormetiazol/análisis , Difenhidramina/análisis , Cromatografía de Gases y Espectrometría de Masas/métodos , Humanos , Lidocaína/análisis , Metadona/análisis , Nicotina/análisis , Sensibilidad y Especificidad , Solventes , Tramadol/análisisRESUMEN
Sorption of nitroglycerin, isosorbide dinitrate, diazepam, and clomethiazole edisylate (chlormethiazole) to polyvinyl chloride (PVC) i.v. administration sets with and without cellulose propionate burettes and to polybutadiene (PBD) sets with and without methacrylate butadiene styrene (MBS) burettes was studied. All drugs (except chlormethiazole) were diluted with 0.9% sodium chloride injection (NS) in glass bottles or in the burette chambers. Initial samples of each solution were obtained from the bottle or from the burette, and effluent samples were collected at various times up to 240 minutes from the sets without burettes and up to 90 minutes from the sets with burettes. For nitroglycerin, flow rates of 0.5 and 1.0 mL/min were used without the burette. The effect of priming the tubing before adding drug to the burette was studied for diazepam. Triplicate samples were analyzed for nitroglycerin and isosorbide dinitrate by high-performance liquid chromatography and for diazepam and chlormethiazole by ultraviolet spectrophotometry. Up to 50% potency of chlormethiazole and nitroglycerin, 15-25% of isosorbide dinitrate, and 13-20% of diazepam was lost to PVC sets without burettes, and an additional 10-15% loss of each drug resulted when PVC sets with burettes were used. Less sorption of nitroglycerin to the PVC sets occurred at the higher flow rate, but flow rate through the PBD sets did not affect sorption. Priming the tubing before adding diazepam to the burette did not affect final drug delivery. No loss to PBD sets was observed for nitroglycerin, isosorbide dinitrate, and diazepam; loss of chlormethiazole to PBD was 7-13%. Drug potency in effluent from PBD sets was not affected by presence or absence of a burette.(ABSTRACT TRUNCATED AT 250 WORDS)
Asunto(s)
Butadienos , Preparaciones Farmacéuticas/análisis , Polímeros , Cloruro de Polivinilo , Polivinilos , Adsorción , Clormetiazol/análisis , Diazepam/análisis , Elastómeros , Infusiones Parenterales/instrumentación , Dinitrato de Isosorbide/análisis , Nitroglicerina/análisisRESUMEN
The dynamics of the interaction of clomethiazole edisylate (1) with polyvinyl chloride and cellulose propionate, the main plastics used in the manufacture of infusion bags and sets, was examined. An experimental system in which the plastic was either open or closed to the environment was used to determine the relative contribution of the sorption and permeation processes to loss from solutions of clomethiazole edisylate (I) in contact with the plastic infusion systems. Sorption by the plastic infusion materials accounted for most of the drug loss, while permeation into the external environment accounted for the remainder. The sorption and permeation into and through polyvinyl chloride was temperature dependent. The diffusion coefficient and permeation rate constant both increased with temperature, while the polyvinyl chloride-water partition coefficients were independent of temperature. The activation energy for the diffusion in polyvinyl chloride was 13.5 kcal/mol. The permeability of the infusion bag plastic and the evaporation across an unstirred air boundary layer adjacent to the external surface of the plastic both appeared to contribute to the overall diffusional resistance encountered in the permeation process. The plastic-water partition coefficients are independent of initial concentration, suggesting that the concentration-dependent loss of the drug from solutions stored in plastic infusion bags and burets is a result of the greater diffusivity of the drug in the plastic at the higher initial concentrations. Plasticization of the polymers by the drug is indicated by the increase in the diffusivity of the drug in polyvinyl chloride and cellulose propionate, the increase in the rate and extent of sorption of a radiolabeled marker (diazepam) by the plastic, and the decreased stiffness of polyvinyl chloride exposed to higher concentrations of the drug.